Researchers at the UK's Loughborough University monitored the energy expenditure and blood sugar levels of 14 men who spent an hour on a bike ride, and an hour in a bath with water heated to 104 degrees Fahrenheit.

While participants expended more calories while cycling, they burned 130 calories while taking a hot bath — equivalent to how many calories you would burn on a half-hour walk. Yes, you could feasibly skip going on a walk and sit in hot water for an hour instead.

While participants' blood sugar levels were about 10 percent lower after a bath than they were after the bike ride, bathing was shown to have a similar anti-inflammatory response on the body to exercise.

INSIDER spoke to research associate Steve Faulkner, who worked on the study, to learn more about how a hot bath can accelerate calorie-burning — and how to burn even more.

While Faulkner said there's "no definitive answer" for how frequently to take a hot bath to burn more calories at this stage of research, he suggests that regular baths can have similar benefits to regular exercise.

"In a similar way to exercise, it may be that [a hot bath] three to five times per week for ~60 minutes would be necessary," he told INSIDER.

However, it's not entirely clear whether staying in a hot bath for longer than an hour will make you burn more calories — or whether the water needs to stay at a constant temperature to burn the most calories.

"From our data it looks as though as body temperature begins to equilibrate that the rate of calorie burn also levels out," he said. Essentially, your body burns more calories when it is hotter.

As for the water temperature, Faulkner said his research team chose 40 degrees Celsius (104 degrees Fahrenheit) so the body would get hot enough to trigger molecular responses that they believe "are important in the use of heat to maximize health benefit."

"It's possible that warmer water could have a larger effect" on burning more calories, he said, "but it would also likely become very uncomfortable very quickly!"

The researchers aren't exactly sure how heat helps the body burns calories just yet. Though Faulkner believes "a likely explanation [for this] is there is an increased energy demand to maintain heat balance," to ensure the body doesn't get too hot or cold, which "causes an increase in calorie burn."

In other words, to deal with external heat, the body has to work harder to balance its internal temperature — which could be accelerating calorie-burn. At this stage, though, Faulkner said more investigation is needed to clarify the idea.